The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingSeat position airbag sensor circuit malfunction
Description
The seat position sensor circuit consists of the center airbag sensor and the
seat position sensor.
Dtc b1653/35 is recorded when a malfunction is detected in the seat position
sensor circuit.
Wiring diagram
Inspection procedure
Check for dtc
Turn the ...
Removal (2005/11-2006/01)
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove front door scuff plate lh
Using a screwdriver, detach the 10 cla ...
Sliding roof switch assembly
Removal
Disconnect cable from negative battery terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove map light assembly
Using a clip remover, detach the 4 ...